Aircraft designs have been, and are, making increased use of electrical and electronic systems to perform functions which may be necessary for the continued safe takeoff, flight, mission execution, and landing of the aircraft. The possible susceptibility of these systems to malfunction and/or failure, when exposed to High Power Microwaves (HPM), has resulted in the need to test the entire aircraft to HPM environments and ensure that the electrical and electronic systems are adequately shielded.
As is well known in the art, during operation, a magnetron will oscillate. High frequency tubes have a fast rise time requirement that actually is conducive to short pulses while low frequency magnetrons have a relatively slower rise time requirement. Accordingly, to achieve proper initiation of oscillation for a low frequency magnetron, typically the pulse applied by the modulator in the circuit must have a relatively slow rate of rise in the transition region, i.e., the region in which the magnetron begins to oscillate. If the applied pulse rises too rapidly in the critical region misfiring may occur, e.g., the tube may go into oscillation in the wrong mode. Any misfiring may be accompanied by a high voltage arc-over inside the tube.
It is to be appreciated that the requirement for a slowly rising modulator pulse is incompatible with the generation of a very short pulse. By using conventional techniques, it has never been possible to operate a magnetron with pulses as short as 40 nanoseconds, and for this reason pulse compression systems have been primarily used to obtain a high range resolution.
One known related prior art reference is U.S. Pat. No. 4,051,439 while a couple of other known related references include 600 kV Modulator Design for the SLAC Next Linear Collider Test Accelerator, K. Harris, J. de Lamare, V. Nesterov and R. Cassel, July 1992, 4 pages, and Don't be fooled by risetime specs on pulsed mircowave tubes. The Darlington modulator is the key to producing narrow pulses. J.T. Tymann et al., Electronic Design 17, Aug. 16, 1969, pages 191-193.